Ladder jack

ABSTRACT

A ladder jack consisting of a beam having a hook at one end engageable over a ladder rung and adapted to support a scaffold plank thereon, a link pivoted at one end to the opposite end of the beam, a hook at the opposite end of said link engageable over a relatively higher rung of the ladder, the link being adjustable in length to level the beam in various positions of use, and a connection joining the hook ends of the beam and link to permit limited free relative movement therebetween.

United States Patent [191 Narkie Sept. 18, 1973 1 LADDER JACK [76]Inventor: Walter E. Narkie, 126 W. 5th St.,

Kansas City, Mo.

22 Filed: Jul zl, 1971 211 Appl. No.: 164,563

52 us. Cl. .Q 248/238 511 Int. Cl. F16!!! 13/00 [58] Field of Search248/238, 309, 353, 248/354 L, 242; 287/58 R [56] References Cited UNITEDSTATES PATENTS 1,332,385 3/1920 Dunlap 248/238 1,107,876 8/1914 Ballard.287/58 R 966,852 8/1910 Norton. 248/238 X 569,645 10/1896 Jones 248/2381,042,192 10/1912 BOiiOt 248/238 328,999 10/1885 Ballman 248/238 393,51211/1888 Long 248/238 608,629 8/1898 Wood 248/353 2,686,648 8/1954 Oehler248/309 Primary Examiner-William H. Schultz Attorney-John A. Hamilton [57] ABSTRACT A ladderjack consisting of a beam having a hook at one endengageable over a ladder rung and adapted to support a scaffold plankthereon, a link pivoted at one end to the opposite end of the beam, ahook at the opposite end of said link engageable over a relativelyhigher rung of the ladder, the link being adjustable in length to levelthe beam in various positions of use, and a connection joining the hookends of the beam and link to permit limited free relative movementtherebetween.

7 Claims, 14 Drawing Figures PATENTEU SE" 8 I878 SHEET 2 [IF 2 INVENTOR.h/fer Adv/m9 E? Fig/11 1913 1 19 13 Aria/way- LADDER JACK This inventionrelates to new and useful improvements in ladder jacks, ladder jacksconstituting brackets adapted to be mounted on ladders to supportscaffolding planks. In common practice, two ladders are usuallyemployed, each carrying a jack, with a scaffold plank extending betweenand supported by said two jacks. They are commonly used by painters,carpenters, and others for both interior and exterior work on buildmgs.

Among the objects of the present invention are the provision of a ladderjack of the general character described which distributes the scaffoldload between two rungs of each ladder, rather than imposing the entireload on a single rung, which is freely adjustable to level the scaffoldplank despite variation in the slope of the ladders, which can bepositioned to dispose the scaffold plank either inside or outside of theladder, with respect to its slope, which may be easily carried up aladder and applied to the rungs thereof in a one-handed operation, whichcompensates for variations in the spacing between the rungs of theladder, and which may be folded compactly for convenience of storage andtransportation.

Other objects are simplicity and economy of construction, andefficiency, dependability, and safety of operation.

With these objects in view, as well as other objects which will appearin the course of the specification, reference will be had to theaccompanying drawing, wherein:

FIG. 1 is a reduced sectional view taken on line ll-I of FIG. 2,constituting a side elevationalview of a ladder jack embodying thepresent invention, shownoperatively applied to the outside of a ladderand supporting a scaffold plank,

FIG. 2 is an enlarged fragmentary top plan view of the parts as shown inFIG. 1,

FIG. 3 is an enlarged side elevational view of the jack link only, shownin a pivoted position assumed thereby when adjusting the length thereof,

FIG. 4 is a further enlarged fragmentary view similar to FIG. 3 butshowing the link parts in locked position,

FIG. 5 is a sectional view taken on line V.-V of FIG.

FIG. 6 is a view similar to FIG. 1, but showing the jack mounted on theinner side of the ladder,

taken on line VII-VII of FIG. 1,

FIG.. 8 is an enlarged, fragmentary sectional view taken on lineVIII-VIII of FIG. 1,

'FIG. 9 is a fragmentary sectional view taken on line IX-IX of FIG. 7,

FIG. 10 is a perspective view of a ladder jack of slightly modifiedconstruction, shown operatively mounted on the inner surface of aladder,

FIGS. l1, l2, and 13 are enlarged sectional views taken respectively onlines XI-XI, XII-XII, and XIII- -XIIl of FIG. 10, and I FIG. 14 is afragmentary sectional view taken on line XIV-'-XIV of FIG. 13.

Like reference numerals apply to similar parts throughout the severalviews, and the numeral 2 applies generally to a ladder including a pairof side rails 4 (one shown) connected at longitudinally spaced apartpoints by rungs 6 extending at right angles thereto. In most ladders thespacing of the rungs is generally standardized at one foot, but issubject to some manufacturing variation, and also to variation by bowingor warping of the rungs themselves. The ladder jack forming the subjectmatter of the present invention, in the form thereof shown in FIGS. 1-9consists generally of a frame 8 carrying a slide 10, a beam 12, and alink 14. Frame 8 consists of two elongated rods 16 disposed in closelyspaced side-by-side relation and connected rigidly at spaced apartpoints of their lengths by spacers 18, and adapted to lie against therungs 6 of the ladder, longitudinally of said ladder. At their upperends, rods 16 are spread divergently apart, and each is formed at itsupper end to present a downwardly opening hook 20 adapted to be engagedover one of said rungs, as shown. Generally, said frame should be ofsuch length as to extend past the second rung below the rung on whichhooks 20 are engaged.

Slide 10 is formed of sheet metal, and is slidably mounted for freemovement longitudinally along the lower portion of frame 8. It includesa base wall 22 parallel to frame rods 16 and adapted to lie against aladder rung, and a guideway 24 through which rods 16 are inserted. Saidguideway includes a center wall 26 (see FIG. 8) disposed between rods116, which limits the movement of the slide on the rods by engagementthereof with a pair of rod spacers 18 of the frame. Also affixed to basewall 22 of the slide are a .pair of downwardly opening hook members 28adapted to engage over the ladder rung 6 adjacent thereto, usually thesecond rung below that engaged by upper hooks 20. The free slidabilityof slide 10 on frame 8 permits the upper and lower hooks to accommodatethemselves accurately to the rungs despite variations in the spacing ofsaid rungs, since as will appear both hooks must carry a portion of thescaffold load. Also affixed to slide 10, at the side thereof oppositefrom hooks 28, is a planar ear 30 having formed therein a notch 32 (seeFIG. 9)

which is inclined upwardly toward :its open end, in a direction awayfrom hooks 28. A locking bar 34 is pivoted at its upper end to ear 30above notch 32, as at 36, and normally hangs downwardly by gravity sothat its lower end obstructs the exit portion of said notch (see FIG. 9

, otal about its axis therein. Lock bar 34 must be pivoted upwardly outof the way before said bolt can be inserted into said notch, but once ithas been inserted, said lock bar returns by gravity to its normallocking position as shown, to prevent accidental disengagement of saidbolt from said notch by shaking, vibration, lifting of the beamindependently of the rest of the jack, or otherwise. The beam projectshorizontally outwardly from the plane of the ladder, as shown, and ispivoted toits outer end, as by bolt 44, to the lower end of link 14, ona transverse horizontal axis. I

Link 14 consists of an upper portion 46 and a lower portion 48. Upperportion 46 consists of a pair of closely spaced apart parallel bars .50rigidly interconnected adjacent their upper ends by a spacer 52 (seeFIG. 3), and by a U-shaped connection 53, and having their extreme upperend portions bent into diverging relation and pivoted by bolts 54 to apair of ears 56 welded respectively to frame rods 16 adjacent upperhooks 20. Lower section 48 of the link is pivoted to beam 14 at 44, andextends slidably and pivotally between bars 50 of the upper section. Akeeper ring 58 encircles upper section 46 above the lower end thereofand is welded or otherwise affixed thereto. Lower section 48 extendsthrough said keeper ring, and is provided at its upper end with a T-head60 too large to pass through said ring, whereby the link sections areretained in assembly. Said ring is sufficiently large, however, topermit a limited degree of relative transverse pivotal movement of thelink sections, as shown in FIG. 3. A bolt 62 is affixed in and extendstransversely between bars 50 of upper link section 46 at the lower endthereof, said bolt being adapted to be engaged in any one of a series ofnotches 64 formed in the upper edge of lower link section 48, the openends of said notches being inclined toward the lower end of the link.The effective length of the link may thus be altered at will byrelatively pivoting lower link section 48 in keeper ring 58 of the uppersection, as shown in FIG. 3, to free bolt 62 from the notch 64 in whichit is then engaged, sliding the link sections longitudinally until bolt'62 is aligned with the notch 64 corresponding to the desired length,and again straightening the link to engage the bolt in the new notch.The inclination of the notches provides that any tensile stress in thelink will hold bolt 62 securely in any notch into which it has beeninserte'd. However, to prevent any possibility that the bolt could beshaken, vibrated, or otherwise accidentally disengaged from any ofnotches 64, there is provided also a locking ring 66 loosely encirclinglink 14 between keeper ring 58 and bolt 62. Said locking ring slidesdownwardly along the link by gravity whenever the link is straight,until it engages the head and nut of bolt 62, and in this positionprevents relative pivoting of the link sections to disengage said boltfrom notches 64. Said locking ring must be manually elevated along thelink to a position adjacent keeper ring 58, as shown in FIG. 3, topermit relative pivoting of the link sections. The locking actionthereof is entirely automatic.

In use, bolt 42 of beam 12 is first inserted in ear notch 32 of slide10, as already described, and the jack is then carried up the ladder bya workman. This may be done easily with one hand, the jack beingprovided with a handle 68 welded to frame ears 56 for this purpose.Upper hooks 20 and lower hooks 28 are then engaged over appropriaterungs 6 of the ladder, as shown. Of course, as the jack is carried upthe ladder, the upper and lower hooks will not be properly spaced forthe rungs since slide will at that time move to its lowermost positionon frame 8', said slide then engaging the lowermost frame spacer 18A(see FIG. 7), but the frame, beam and link will nonetheless be held inproper general relationship tofacilitate one-handed application of bothsets of hooks to the rungs. As the hooks are applied, slide 10 will moveupwardly on the frame to a position in which it is freely movable on theframe, thus insuring full weight-supporting engagement of both sets ofhooks with their respective rungs.

Link 14 is then adjusted in length, as described above, to bring beam 12into a horizontally level position. Obviously, the jack may be appliedto the outer side of the ladder as shown in FIG. 1, so that beam 12projects outwardly from the ladder, or to the inner side of the ladderas shown in FIG. 6, so that beam 12 projects inwardly from the ladder,as may be desired in any particular job as dictated by considerations ofaccessibility of the work area. Obviously, the FIG. I arrangementrequires link 14 to be set much longer than the FIG. 6 arrangement.Also, in either case, the adjustability of the link permits levelling ofbeam 12 despite variations in ladder slope. Lower link section 48 couldobviously be provided with as many notches 64 as might be desired.Another ladder, similarly equipped with a ladder jack, is set up inspaced relation from the first, and a scaffold plank extended betweenand supported by beams 12 of the two jacks.

It will be seen that the jack as shown and described has severaladvantageous features. It will be seen that the load carried by theinner end of beam 12 is transmitted through slide 10 directly to lowerhooks 28 and the ladder rung 6 engaged thereby, while the load carriedby the outer end of the beam is transmitted by link 14 to upper hooks 20and the separate rung 6 engaged thereby. Thus the scaffold load isdistributed between and carried by two ladder rungs. This represents asubstantial improvement in safety and load capacity over the usual jack,which is supported by only a single ladder rung. Furthermore, thiscondition prevails despite possible variations in the rung spacing ofthe ladder, or bending or deformation of the rungs, due to the freeslidability of slide 10 on frame 8. Safety of the jack is furtherenhanced by locking bar 34 and locking ring 66, which respectivelyprevent accidental disengagement of bolt 42 from notch 32, andaccidental extension of link 14, either of which occurrences could causedangerous dropping or tilting of the scaffold plank. Both lockingdevices operate automatically, without attention by the workman. It isnot necessary to the basic operation of the jack that beam 12 bedisengageable from frame 8 at all, but it does permit the entire jack tobe folded into a compact space for ease and convenience of storage andtransportation. The jack may be applied with equal facility to eitherthe inner or outer surface of a ladder, and may be easily carried up aladder and applied thereto by a single workman in a one-handedoperation.

FIGS. 10-14 show a somewhat simplified modification of the structureshown in FIGS. 1-9. Its operation and construction is generally similarto those of FIGS. 1-9, corresponding parts being indicated bycorresponding primed numerals. However, as clearly shown in FIG. 10,upper hooks 20' are rigidly affixed to the upper end of link 14 insteadof being pivoted thereto, and lower hooks 28 are rigidly affixed to beam12' instead of being pivoted thereto. Also, instead of the frame 8 andslide 10 shown in FIGS. 1-9 for connecting the upper and lower hooks,FIG. 10 shows a chain 72 connected at its upper end to an ear 74 weldedto the upper end of link 14' and connected at its lower end by a snapfastener 76 to an eye 78 welded to beam 12 adjacent hooks 28'. Saidchain serves the same general purpose as frame 8 and slide 10 in FIGS.l-9, holding the beam and link in generally proper relationship as thejack is carried up a ladder, but being of such length as to be slack asshown when the upper and lower hooks are engaged on the ladder rungs, topermit said hooks to accommodate themselves to variably spaced rungs.Here again, it is not essential that the chain be provided withdetachable connection 76, and the jack can be folded for transportationor storage without it, but it does permit the jack to be assembledaround a scaffold plank already in place whenever this may be desired.The detachability of beam 12 from slide serves the same purpose in FIGS.l-9. Link 14 is generally similar in structure and operation to link 14,consisting of an upper section 46' and a lower section 48' extendinginto slidable overlapping relation, a keeper ring 58' welded to theupper end of lower section 48' to permit relative sliding and pivotalmovement between said sections, a second keeper ring 80 (not used inFIGS. ll-9) affixed to the lower end of upper section 46' and encirclinglower section 48 to limit the relative pivotal movement of the sectionsto that amount necessary to release a bolt 62' fixed transversely in thelower end of section 46' from any of a series of longitudinally spacednotches 64' formed in lower section 48', keepers 58' and 80 also servingto retain the link sections in assembly, and a locking ring 66' looselyencircling the link between keepers 58' and 80. The length of link 14may be adjusted substantially identically as that of link 14. The onlymaterial difference in actual operation of the species of FIGS. 10-14from that of FIGS. ll-9 is that in FIGS. 10-14 it will be seen that inaccommodating themselves to ladder rungs 6' of different spacings, upperand lower hooks and 28 must be free to pivot on said rungs. This speciesis therefore not well adapted for use with ladders having flat,step-like rungs instead of the rungs shown which are round incrosssectional contour. In FIGS. 1-9, on the other hand, the hooks havea fixed, non-movable relation to the rungs, and hence may beconfigurated to conform to rungs of any cross-sectional contour.

f While I have shown and described certain specific embodiments of myinvention, it will be readily apparent that many minor changes ofstructure and operation could be made without departing from the spiritof the invention.

What I claim as new and desire to protect by Letters Patent is:

1. A ladder jack comprising: i

a. a lower hook adapted to engage downwardly over a relatively lowerladder rung,

b. a beam connected at one end of said lower hook to extend horizontallyoutwardly from said ladder, transversely to the plane of said ladder,whereby it is positioned to support a scaffold plank,

c. anupper hook adaptedto engage downwardly over a relatively higherladder rung, and I a link connected at one end to said upper hook andpivoted at its opposite end to the end of said beam remote from saidladder, on a horizontal transverse axis, said link being adjustable inlength, and comprising an upper section connected to said upper hook, alower section pivoted to said beam, said upper and lower sectionsextending into slidably overlapping relation, said lower section havinga series of longitudinally spaced, transversely open-. ing notchesformed therein, a pin fixed transversely in said upper section andengageable selectively in any of said notches, keeper means connectingsaid upper and lower sections at a point spaced upwardly from said pinfor relative movement about an axis transverse to said link, wherebysaid pin may be disengaged from any of said notches, and locking meanscomprising a locking ring loosely encircling both sections of said linkintermediate said pin and said keeper, said locking ring being movablealong said link by gravity to a position adjacent said pin, whereby toprevent relative pivotal movement of said link sections and to securesaid pin in one of said notches, but being manually elevatable alongsaid link to a position adjacent said keeper, whereby to permit relativepivotal movement of said link sections.

2. A ladder jack as recited in claim 1 with the addition of connectingmeans joining the ends of said link and beam connected respectively tosaid upper and lower hooks and permitting limited free relative movementof said link and beam about their pivotal connection, whereby tomaintain said link. and beam in generally normal relation forconvenience in carrying the jack up a ladder and applying it thereto,and to permit said upper and lower hooks to accommodate themselves toladders having varying spacing between rungs.

3. A ladder jack as recited in claim 2' wherein said connecting meanscomprises:

a. a generally vertical frame having said upper hook fixed at the upperend thereof, said link beingpivoted to said frame on a horizontaltransverse axis adjacent said upper hook, and.

b. a slide movable vertically along said frame below said upper hookbetween fixed limits, said lower hook being affixed to said slide andsaid beam being pivoted to said slide on a horizontal transverse axis,said slide being disposed intermediate the limits of its movement onsaid frame when said upper and lower hooks engage rungs of said ladder.

4. A ladder jack as recited in claim 3 wherein said beam is detachablyconnected to saidslide, whereby to permit folding of said jack.

5. A ladder jack as recited in claim 3 wherein said beam is provided atthe end thereof joining said slide with a fixed transverse pin, and saidslide is provided with a notch inclined upwardly toward its open end forreceiving said pin, and with the addition of a locking member pivotedfreely to said slide above said notch and movable by gravity to aposition above said beam adjacent said pin, whereby to prevent removalof said pin from said notch. y i

6. A ladder jack as recited in claim 2 wherein said upper and lowerhooks are adapted to engage ladder rungs for pivotal movementthereabout, and wherein said link and beam are rigidly affixedrespectively to said upper and lower hooks.

7. A ladder jack as recited in claim 6 wherein said connecting meanscomprises a flexible connector extending between and joining said linkand said beam at points adjacent said hooks, said connector being ofsuch length as to be slack when said hooks engage rungs of said ladder.

k 6' I 4' l

1. A ladder jack comprising: a. a lower hook adapted to engagedownwardly over a relatively lower ladder rung, b. a beam connected atone end of said lower hook to extend horizontally outwardly from saidladder, transversely to the plane of said ladder, whereby it ispositioned to support a scaffold plank, c. an upper hook adapted toengage downwardly over a relatively higher ladder rung, and d. a linkconnected at one end to said upper hook and pivoted at its opposite endto the end of said beam remote from said ladder, on a horizontaltransverse axis, said link being adjustable in length, and comprising anupper section connected to said upper hook, a lower section pivoted tosaid beam, said upper and lower sections extending into slidablyoverlapping relation, said lower section having a series oflongitudinally spaced, transversely opening notches formed therein, apin fixed transversely in said upper section and engageable selectivelyin any of said notches, keeper means connecting said upper and lowersections at a point spaced upwardly from said pin for relative movementabout an axis transverse to said link, whereby said pin may bedisengaged from any of said notches, and locking means comprising alocking ring loosely encircling both sections of said link intermediatesaid pin and said keeper, said locking ring being movable along saidlink by gravity to a position adjacent said pin, whereby to preventrelative pivotal movement of said link sections and to secure said pinin one of said notches, but being manually elevatable along said link toa position adjacent said keeper, whereby to permit relative pivotalmovement of said link sections.
 2. A ladder jack as recited in claim 1with the addition of connecting means joining the ends of said link andbeam connected respectively to said upper and lower hooks and permittinglimited free relative movement of said link and beam about their pivotalconnection, whereby to maintain said link and beam in generally normalrelation for convenience in carrying the jack up a ladder and applyingit thereto, and to permit said upper and lower hooks to accommodatethemselves to ladders having varying spacing between rungs.
 3. A ladderjack as recited in claim 2 wherein said connecting means comprises: a. agenerally vertical frame having said upper hook fixed at the upper endthereof, said link being pivoted to said frame on a horizontaltransverse axis adjacent said upper hook, and b. a slide movablevertically along said frame below said upper hook between fixed limits,said lower hook being affixed to said slide and said beam being pivotedto said slide on a horizontal transverse axis, said slide being disposedintermediate the limits of its movement on said frame when said upperand lower hooks engage rungs oF said ladder.
 4. A ladder jack as recitedin claim 3 wherein said beam is detachably connected to said slide,whereby to permit folding of said jack.
 5. A ladder jack as recited inclaim 3 wherein said beam is provided at the end thereof joining saidslide with a fixed transverse pin, and said slide is provided with anotch inclined upwardly toward its open end for receiving said pin, andwith the addition of a locking member pivoted freely to said slide abovesaid notch and movable by gravity to a position above said beam adjacentsaid pin, whereby to prevent removal of said pin from said notch.
 6. Aladder jack as recited in claim 2 wherein said upper and lower hooks areadapted to engage ladder rungs for pivotal movement thereabout, andwherein said link and beam are rigidly affixed respectively to saidupper and lower hooks.
 7. A ladder jack as recited in claim 6 whereinsaid connecting means comprises a flexible connector extending betweenand joining said link and said beam at points adjacent said hooks, saidconnector being of such length as to be slack when said hooks engagerungs of said ladder.